I began performing breathwork when I started doing the Wim Hof Method. I continue to perform my breathwork much the same as Wim and his students do, but no longer finish with pushups. I do, however, hold my breath when doing Stronglifts. I started out only being able to hold my breath for about a minute, but have worked up to being able to hold it for as long as 3 minutes and 30 seconds.
Below is a spreadsheet containing all the data associated with my breathwork. It contains the following categories:
Date, Time Session 1, Times Session 2, Time Session 3, Time Session 4, Pushups